Preparation of beta-(nu, nu-diphenyl)-amino propionic acid



beta carbon atom of beta-propiola'ctone.

' Patented Apr. 4, 195.0

PREPARATION OF BETA- (N,N-DIPHENYL) AMINO PROPIONIC ACID Thomas L. Gresham and Ralph A. Bankert, Akron, Ohio, asslgnors to The B. F. Goodri Company, New York, N. Y., a corporation of New York No Drawing.

Application January 2, 1947, Serial No. 719,916

3 Claims. (01. zoo-51s) I This invention relates .to the preparation of beta- (NN-diphenyl) -amino propionic acid. (also called beta-(NN-diphenyl) -alanine), by the reaction of the organic compound, beta, propiolactone, with the secondary diarylamine, diphenyl amine. It is disclosed in U. S. Patent 2,356,459 to Frederich E. Kiing that beta-lactones, that is, lactones or inner esters of beta-hydroxy carboxylic acids, may be obtained in good yields by the reaction of a ketene with an aldehyde or ketone. In this manner beta-propiolactone (also called hydracrylic acid lactone) which has the structure cn,cn,-c=o

. is economically obtained from ketene and formaltones will react with certain organic compounds containing one or more hydrogen-bearing trivalent nitrogen atoms to form N-substituted carboxylic acid amides.

We have now discovered, surprisingly, that beta-propiolactone will react with the secondary diarylamine, diphenylamine, to form beta-(N,N- diphenyl) -amino propionic acid, this reaction being quite unlike the reactions described in the above-mentioned applications since it involves the linkage of an amino nitrogen atom to the This reaction provides a convenient and economical method of preparing beta-(NN-diphenyl) -amino propionic acid, which has not heretofore been prepared.

The reaction of this invention, leading to the formation of beta-(N,N-diphenyl) -amino propionic acid, is illustrated by the following equation representing the reaction occurring when beta-propiolactone is reacted with diphenylamine:

In carrying out the reaction a wide variety of reaction procedures and conditions may be used. When the reaction temperature is above the melting point of diphenylamine, the reaction may be effected simply by mixing the reactants with eflicient stirring and then allowing reaction to occur or by adding one of the reactants to the other during the course of the reaction in which event the addition of the beta-propiolactone to the diphenylamine is preferred since the lactone tends to polymerize in the presence of small amounts of basic substances, thereby reducing the quantity of lactone available for the reaction. Another procedure, especially desirable when the reaction is carried out below the melting point of diphenylamlne consists in dissolving or dispersing the diphenylamine in a solvent or diluent which does not react appreciably with beta-propiolactone and then adding beta-propiolactone either as such or in solution in the same or a miscible medium. Solvents and diluents useful in this connection include benzene and other hydrocarbons, ether, acetone, toluene, and other natural and substantially inert solvents and the like.

It has been found that a zinc chloride catalyst or other metal chloride catalyst such as aluminum chloride, although not necessary for the completion of the reaction, will accelerate the reaction, this being especially true where a solvent is employed with the reactants.

The temperature at which the reaction is conducted is not critical and may be varied considerably. It has been found that the best yields from this reaction are obtained when temperatures of approximately 140 C. are maintained. However, temperatures from 5 C. to 180 C. have been used with good results, but temperatures above C. and especially from to C. are preferred.

Quantities of reactants are likewise not critical although it is generally desirable to employ equimolecular quantities of the diphenylamine and beta-propiolactone, or a molecular excess of diphenylamine.

The reaction product is obtained as a slightly yellow oil which solidifies on stirring. It is easily purified by crystallization from aqueous alcohol solution and the pure compound is a. white solid with a melting point of 111 to 113 C. The purifled reaction product has been found to be beta- (N,N-diphenyl) -amino propionic acid.

This new compound, beta- (N,N-dipheny1) amino propionic acid, formed in the reaction described hereinabove finds utility in diverse fields. It can be used as an intermediate in the preparation of many valuable organic compounds. For example, it may be reacted with alcohols under aeoaus 3 the usual ssterification conditions to produce esters of beta-(NJI-diphenyD-amino propionic acid It has also been shown to be a valuable plant regulant, for example, when 1 to 5% of the compound is dissolved in a solvent such as keroune, the resulting solution is effective in weed-killing.

In addition, it has been found to be especially valuable in the propagation of root systems. For

example, ten four-inch rose cuttings were dipped for thirty seconds in an aqueous dispersion conamino propionic acid for each c. c. of water present, the dispersions also containing 0.025% by weight of sodium lauryl sulfate (Aquarex D) as taining 0.125 milligrams of beta-(N,N-diphenyl) dispersing agent. The cuttings were then placed in clean sand along with ten control cuttings. The cuttings were watered daily and after eight days were examined for the extent of rooting. Of the ten cuttings treated with the acid, eight were growing with good root systems while all the untreated cuttings were rotted.

The more detailed preparation of beta-(NH- diphenyD-amino propionic acid is illustrated by the following examples, wherein parts are given by weight. There are, of course, many other reaction procedures which are operative other than these specific examples.

Example I Example 11 258.5 parts (1.5 moles) of diphenylamine and 4 72parts(1mole) ofbeta-propiolactonearereacted by adding the beta-propiolactone to the diphenylamine in a dropwise manner without the addition of heat. After the beta-propiolactone is added. the reaction product is added to a mechanically stirred 10% sodium hydroxide solution. The unreacted diphenylamine is filtered oil and the filtrate extracted with ether to remove any diphenvlamine which remains after the filwring. The extracted filtrate is then acidified with cone. vliICl and a white solid precipitates. The precipitate is crystallized from aqueous alcohol solution and 139 parts (57.7% yield) of beta- (NN-diphenyl) -amino propionic acid (M. P. -113 C.) are formed.

When this example is repeated in the presence of acetone, as solvent for the reactants, and in the presence of 0.5 part of zinc chloride as catalyst, the same compound is again obtained.

We claim: 1. The method which comprises reacting diphenylamine with beta-propiolactone and recovering primarily beta-(N,N-diphenyl) -amino propionic acid.

2. The method which comprises reacting diphenylamine with beta-propiolactone in a mutual solvent and in the presence of a zinc chloride catalyst and recovering primarily beta- (N,N-diphenyl) -amino propionic' acid.

3. The method which comprises reacting diphenylamine with beta-propiolactone at a temperature of to C. and recovering primarily beta (N.N diphenyl) amino propionic acid.

THOMAS L. GRESHAM. RALPH A. BANKERT.

REFERENCES CITED The following references are of record in the file of this patent:

Basler: Ber. 'Deut. Chem., vol. 17 (11), page 1503 (1884).

Stolle: Journal der Prakt. Chem., vol. 198, N. F. 90, pages 273-275 (1914). (Beilstein Handbuch der Org. Chem., vol. 12 (supp) page 264, 4th ed.) 

1. THE METHOD WHICH COMPRISES REACTING DIPHENYLAMINE WITH BETA-PROPIOLACTONE AND RECOVERING PRIMARILY BETA-(N,N-DIPHENYL)-AMINO PROPIONIC ACID. 